Electric generator



Sept. 16, 1930. H. J. GRAHAM ELECTRIC GENERATOR Filed June 20, 1927 2 Shets-Shee t 1 W1 TNESS Herberi J Graham, WW ATTORNEYS Sept. 16, 1930.

Filed June 20; 1927 2 Sheets-Sheet 2 WITNESSES fi Herbez g gl aimm, i I BY W wrromzsis.

Patented Sept. 16, 1930 UNITED STATES. PATENT OFFICE HERBERT J. GRAHAM, OP PHILADELPHIA, PENNSYLVANIA, ASSIGNOB TO ELECTRIC SERVICE SUPPLIES COMPANY, 01' PHILADELPHIA, PENNSYLVANIA, A CORPORA- 'I'ION OF PENNSYLVANIA ELECTRIC cmimuroa Application fled J1me 20,

This invention relates to electric generators, and'more particularly to those of the D. C. type such as ordinarily used to furnish current for locomotive headlights.

In the use of electric generators heretofore desi ed for the above, and other, purposes considerable difiicultyhas been experienced in certain kinds of installations with leaking currents. This phenomenon is due to failure v of armature insulation and grounding of one or more generating coils, as a consequence of which separate extraneous circuits are established with the metallic parts of the generator casing, etc., wherein currents are set up because of the faulty,coils. The stray currents so generated are especially troublesome in instances where they are in proximity to other independent circuits because of the electrical interferences set up. v

The object of my invention is to overcome the various difficulties I above enumerated; and this end I attain, as hereinafter fully explained, by a novel armature construction whereby the possibility of grounding of one .or more of the current generating coils through the housing or other metallic parts of the. generator, or any external electrical.

path, is precluded.-

With reference to the drawings, Fig. I is an axial sectional view through the generator conveniently embodyin my invention.

Fig. II is an elevation loo 'ng toward the right hand end of Fig.1, with certain parts broken away, and in section.

Fig. III is a transverse sectional view of the armature taken as indicated by the arrows III-III in Fig. I; and,

Fig. IV is an exploded view showing certain of the parts associated with the armature and commutator of the generator.

The electric" generator chosen for the purpose of illustration herein embodies an annular housin member 10, which supports a number of fie d magnets 11 in spaced angular relation. The inner end of the housing 10 is 'appro riately flanged .as at 12 for attachment tot e casing of a turbine or other prime mover, partly shown at'13. 'The outer end "of the housing member 10 is closed by an annular plate or diaphragm 14 which carries 1927. Serial No. 500,087.

the mountings for the brushes 15, the various appendages of said diaphra 14. being normally protected by a swinga le cover or door 16. The armature shaft 17 is supported. in suitable antifriction bearings provided by the structure 13, one such bearing being shown at 18. The free end of the shaft 17 carries the armature 19 and the commutator 20 to which'the present improvements are more particularly directed.

In accordance with myiinvention, the armature 19 and the commutator 20 are constructed as separate assemblages or units, and supported on a common axle in the form of a sleeve 21 so that they can be removed from the shaft 17 together for the purpose of inspection without necessity for individual dismantling. The sleeve 21 is conically bored as at 22 for forced fitting over the correspondingly-tapered portion 23 of the shaft 17 by virtue of threaded engagement between the latter and said sleeve at 25. In the present instance, the armature 19 embodies a coil mounting or core 26 made up of a multiplicit of annular sheet iron stampin 26a whic are arranged face to face after t e usual manner of laminating in this art. These stamp: ings 260 are peripherally notched as shown at 27 in Fig. III to. jointly provide a series of longitudlnall extending slots or channels for reception an retainment of current generating-coils 28. The laminated coil mounting or armature core 26 is supported on the sleeve 21 through interposition of apair of comparatively'thick insulation collars 29, these being maintained in definite se aration by a tubular s acer 30 of metal. bviously if desired or ound convenient, a single co-extensive sleeve of insulation may be employed in lieu ofthe separate collars 29 between the armature core 26 and the metallic axle member or sleeve 21. The ends of the coil mounting or armature. core 26 are }protected ,by stout disks 31 of insulation whic are centrally a rtured to fit over the collars 29 as shown in I and II, and peripherally notched in conformity with the metalliclaminations 26a, see Fig. IV. These disks 31 may however be extended inward to the sleeve 21 so lating collars 29. The several parts constitutin the coil mounting or armature core 26 are he d in assembl by a number of circumferentially arrange tubular bolts or rivets 32 which traverse lon 'tudinal openings in the structure afiorded y complemental internal and external peripheral notches of the arts 26, 31 and 29, respectively, see FigsII and IV. The ends of the tubular rivets 32 are ex" panded to provide heads 33, which, as shown in Figs. I and III, overlap the lines of juncture between the insulating collars 29 and disks 31, at their contiguous outer faces, thereby securing the parts rigidly together as a unit, with the tubular spacer 3'0 clamped in position between the aforesaid collars 29. By this construction it will be apparent that the armature 19 can be completely assembled for convenience in initially mounting it on the sleeve 21, or in subsequently removing it therefrom to enable repairs or replacements. It will moreover be apparent that the insulating support or spider formed by the parts 29, 31, serves as an effective barrier against metallic contact between the laminated coil mounting or armature core 26 at the ends as well as between said core and the sleeve 21, thereby offsetting the possibility of grounding of any of the current enerating coils 28 through the shaft 17 and t e generator housing 10. While the above construction involves use of a separable sleeve 21 as the supporting axle for the armature core 26, it is to be understood that the latter may be directly mounted, with interposition of insulation, such as described, upon the shaft 17.

' sleeve 21 is dispensed with, the commutator The commutator 20,- per se, is made up more or less after common practice, i. c. with radially arranged segments 35 whereto the leads of the current generating coils 28 are connected, said segments being insulated from .each other and from the spool-like core piece 36, as clearly shown in .Figs. I and II. The departure from customary construction in the present instance is in connection with the insulation of the commutator unit 20 from the supporting sleeve 21. In cases where the unit 20 may be directly mounted on the shaft 21 with the lnsulation sleeve 37 intervening. As shown 1n Fig. I, the commutator 20 occupics the reduced end portion 21a of the sleeve 21 with interposition'of a bushing 37 of insulation, between the latter and the collar 36. The opposite ends of the commutator 20 are protected by heavy insulating washers 38, 39 (Figs. I, and IV) fitting the sleeve end 210 and abutting the ends of the bushing 37. A tubular spacer 40 (Figs. I and IV) determines the position of the commutator 20 with respect to the armature 19 on the sleeve21; and a clamp nut 41, having threaded engagement 7 with the sleeve and 21a, operates in 0 position to a circumferential shoulder 42 of -t e sleeve 21 to firmly secure the armature 19 andcommutator 20 in place. Thus, b removal of the nut 41 and an associated acing washer 43, the commutatdr 20 and the armature 19 may be successively removed from the sleeve 21 1f required.

From the foregoin it will be apparent that I have provide an efiective barrier against establishment of extraneous circuits fective means are provided that prevent metallic contact or paths for electrical transmission between any of the armature coils 28 and the shaft 17 on which the armature 19 is supported.

It is to be expressly understood however that I do not intend to limit myself to the multipartite construction of the insulation, herein specifically shown and described, to electrically isolate the armature and commutator units 19, 20 from the common axis of rotation or shaft 17, since'it is conceivable within the scope of my invention that these several parts may be readily incorporated into an integral element. Certain of the appended claims are therefore to be construed broadly with this thought in mind. Moreover, my invention may obviously be embodied in the construction of motors or other electrical machinery as well as in generators. The term generator as used in the claims is accordingly to be considered as all inclusive.

Having thus described my invention, I. claim:

1. In an electric -generator,an armature coil mounting, a rotative axle therefor, a

number of axially spaced insulation collars to support the coil mounting and to prevent metallic contact thereof with the axle, spacing meanssurrounding the axle and disposed between the collars to maintain the latter in definite separation, insulation disks to protect the ends of the coil mounting, said disks being centrally apertured to fit over the end insulation collars, and a series of circumferentially-arranged longitudinall -extending securin elements with their en expanded to lap t e junctures between the contiguous faces of the end insulation collars and the insulation disks aforesaid to tie the several parts together.

2. In an electric generator, an\ armature,

a' commutator, a common axle therefor, axially-spaced insulationcollars between the metallic parts of the armature and commutator and the axle, insulation disks at the ends of the commutator, a spacer means about-the axle to determine the relative positions of the armature and commutator on said axle, and an end clamp unit 0 erative 1n opposition to a circumferential s oulder on t e axle to bind the armature, the commutator,- the spacer and the insulation disks together on sand axle.

.core being longitudinally bored to for securely rasse 3. An armature construction comprising a shaft for supportin the armature, a sleeve mounted on the sh laminated disks having a central bore with recesses disposed about said bore, an insulating and supporting structure for said core comprising insulatmg collars axiall spaced and mounted on 'said sleeve, said col ars hav- 1n ho es, a tubular spacing element spacing said insulating collars, axially extendm fasten-. ing elements extending between sai insulating collars to rigidl secure said parts together, and the core aminations fitting over the fastening elements and having theirvrecesses engaging therewith.

11 an electric generator, an armature unit ada ted to be carried upon a rotatable shaft and comprising an armature core, said passage of the rotatable shaft therethrough,

I a said bore being of a diameter ter than that of the shaft, insulation dirranged to respectively cover the exposed end surfaces of the core, means extending longitudinally through the bore of the armature core amping the disks and core together whereby to constitute the same a unit assemblage, and means for insulatingly su g porting the unitary assemblage u n t e rotatable shaft aforesaid, said c ing means being disposed externally of and mg the opposite endsthereof anchored to the last mentioned insulatory supporting means.

-5. In an electric generator, an armature unit ada ted to be carried upon a rotatable shaft an comprising an armature core said core being lon tudinally bored to permit the assage of sai shaft'therethrough, said bore ing of a diameter greater than that of the shaft, insulation disks arran d to res ive- 1y cover theexposed end sur aces of t e core insulating means interposed between said core and theshaft for supporting the former upon the latter in insulated relation, and means extending longitudinally through the bore of the armature ternally of said insulating means for securely clamging together said core, disks and, interpose insulating means, whereby to' constitute the several arts a unitary bly.

In testimony w ereof, I have hereunto signed my name at Philadelphia, Pennsyl- 'vania, this 13th day of June, 1927.

HERBERT J GRAHAM.

, a core unit built up of longitudinally extending peripheral permit the core and arranged ex- 

